First of all, brreeeeaaathhheee! I think this is a little more common than you thing :-)
I had a similar thing happen to me, not on the ice, but while I was in ballet. I was preparing for a very important exam, and for one portion of the exam, I had to perform a variation that had a challenging turn sequence in it. I had the sequence mastered, performed it three times in a row with few mistakes and was feeling confident. Three days before my exam, could barely do a double pirrouette. I went into full blown panic when I realized a double pirrouette was suddenly out of my reach, and the rest of that day was tarnished by my anxiety over the situation. I remember thinking, this is the end of the world, I'm a terrible dancer, my career is over. I, like you, couldn't figure out why I couldn't do turns all the sudden, turns were my strong point! I took the next day off, returned the following day, and everything was fine.
Here is what I think happened - something went wrong, and because your test it so soon, you panicked. Your anxiety filled took over your mindset and you weren't able to reset your thought process and refocus. I would suggest you take the weekend off off and return the first of the week with the attitude of "I can do this."
Good luck, hope I could help a little!